Praktikum Kualitas Air DTPKL: Analisis BOD dan DO. Lab. TPKL-FTP Universitas Jember

Introduction

This tutorial outlines the process of analyzing Biochemical Oxygen Demand (BOD) and Dissolved Oxygen (DO) as part of water quality assessment conducted in the laboratory at Universitas Jember. Understanding BOD and DO is crucial for evaluating organic material in water and the oxygen levels required for aquatic life. This guide provides a step-by-step approach to performing these analyses effectively.

Step 1: Gather Necessary Equipment and Materials

Before starting the analysis, ensure you have all the required equipment and materials:

• BOD bottles (300 mL capacity)
• DO meter or Winkler titration kit
• Incubator set to 20°C
• Water sample (from the source you wish to test)
• Distilled water
• Sodium thiosulfate solution (for DO determination)
• Manganese sulfate and sulfuric acid (for Winkler method)
• pH meter (optional, for measuring pH levels)

Practical Tips

• Always use clean, sterilized containers to avoid contamination.
• Label all samples clearly for accurate tracking.

Step 2: Conduct BOD Analysis

The BOD analysis measures the amount of organic material in a water sample. Follow these steps:

1. Fill the BOD Bottles

   • Fill two BOD bottles with the water sample to the brim to avoid air bubbles.
   • Ensure that no air is trapped, as it can affect the results.

2. Seal and Incubate

   • Seal the bottles tightly.
   • Place the bottles in the incubator set at 20°C for 5 days.

3. Measure Initial DO

   • Before sealing, measure the initial DO of the sample using a DO meter or Winkler method.
   • Record the value for later calculations.

4. Measure Final DO

   • After 5 days, remove the bottles from the incubator.
   • Measure the final DO using the same method as above.

5. Calculate BOD

   • Use the formula:

     BOD = Initial DO - Final DO
     

   • This value represents the oxygen demand exerted by the organic material in the water sample.

Common Pitfalls

• Ensure the incubation temperature is stable; fluctuations can skew results.
• Do not open the bottles between measurements to prevent oxygen exchange.

Step 3: Conduct DO Analysis

Measuring the dissolved oxygen in water is essential for assessing the health of aquatic ecosystems. Here’s how to perform the DO analysis:

1. Prepare the Sample

   • Collect a water sample in a clean bottle, ensuring minimal exposure to air.

2. Add Reagents (Winkler Method)

   • Add 1 mL of manganese sulfate solution to the sample.
   • Add 1 mL of alkaline potassium iodide solution.
   • Mix gently and let it sit for 5-10 minutes.

3. Acidify the Sample

   • After settling, add a few drops of sulfuric acid to the mixture.
   • This reaction will form a colored complex.

4. Titrate the Sample

   • Use sodium thiosulfate solution to titrate the sample.
   • Continue until the solution turns from brown to a light yellow.

5. Calculate DO

   • Record the volume of sodium thiosulfate used.
   • Use the formula to determine the DO concentration.

Practical Tips

• Perform titration slowly to avoid overshooting the endpoint.
• Make sure to calibrate your DO meter or titration setup beforehand.

Conclusion

This tutorial covered the essential steps for conducting BOD and DO analyses in water quality assessments. By following these procedures, you can accurately determine the levels of organic material and oxygen in water samples, which are vital for evaluating aquatic health. For further studies, consider experimenting with different water sources or exploring additional water quality parameters.